Hydroponics are utilized in greenhouse environments for the growing of plants such as tomatoes, peppers, cucumbers, etc. In one form a plug is planted within a starting block, which is (for example) a 3×3 or 4×4 block. Then the starter cube is placed on top of a slab. The block is generally on a concrete floor, the floor is flooded, and the blocks then soak up the water. The floor is flooded and drained in a regimented manner in a propagation stage. Thereafter, the plugs are transported, such as by being loading on a truck and sent to growers, who will take the plant and will cut a hole on the top of the slab and establish a drip line.
In general, the prior art consists of having small starter block cube-like members which are made from what is referred to as “rock wool,” which allows for a wicking action of water and nutrients to be absorbed upwardly into the entire unit. As mentioned above, starter cubes are typically between 3 to 4 inches on each side of the square-like pattern for growing such plants, which is generally done by what is called a propagator. This prior art device described above is distributed by Grodan and is made from a silicon base material which is heated and woven and which has the desirable effect of wicking water; however, rock wool can be less than ideal because it is quite heavy, very expensive to manufacturer (although the raw materials are cheap), and very difficult to dispose of.
Polyurethane foam has been utilized as a growing medium in the past; however, using partially open-cell and open-cell polyurethane foam has resulted in poor consistency of the wicking effect of absorbing water therein throughout the polyurethane material. Described herein are a product and a process for making such a product which provides for a polyurethane-based foam that is conducive to hydroponic environments so as to provide sufficient wicking throughout the foam material to result in a desirable growing medium.